Ingredients for 8 servings:
150gr white flour
150gr potatoes flour
250gr soft butter
250gr sugar
2 whole eggs and 2 egg yolks
1 grated lemon skin
Butter and potatoes flour for pan
Powdered sugar

Preparation:
Grease and flour a 24cm diameter oven pan with high edges.
In a medium mixing bowl beat butter at length using a wooden spoon, till butter results creamy.

Keep beating and add slowly sugar, one egg per time only as soon as the previous is mixed, and finally beat yolks.

Add to mixture sieved flours and lemon skin.

Stir very well mixing gently, than pour all in the oven pan. Dough should fill only 2/3 of oven pan. Bake in 180°C oven for 45 minutes.